The invention relates to portable devices for testing electrical transmission or distribution equipment for the presence of high AC voltages in excess of one kilovolt.
In order to avoid accidental injury and/or equipment damage in the course of operation of or construction or maintenance work on electric power distribution and transmission systems, the work is commonly done after the installations have been disconnected from a source of energy. In order to verify that the equipment or conductors in question are in fact "dead" or disconnected, it is known to provide high-voltage detectors to test the conductor or equipment to verify the absence of high voltage. A line of such detectors is sold by HD Electric Company under the trade designation "TAG." The detector typically includes an insulating housing, which encloses the detection circuitry, and a probe on the housing adapted to make electrical contact with the conductor or other equipment to be tested, the housing being adapted for connection to an insulating "hot stick" to facilitate reaching the conductor or equipment. Different types of probes are utilized for different applications, such as overhead transmission and distribution wires and underground and pad-mounted gear.
In the latter application, certain types of metal enclosed equipment may present grounded surfaces in close proximity to the body of the probe (in the nature of an elongated tube with a conductive tip) and/or the attached voltage detector. For an inexperienced or unknowledgeable user, these grounded surfaces can provide an opportunity for a flashover which could expose the user and/or associated equipment to dangerously high currents.